title: Sensitive and selective detection of OH radicals using Faraday rotation spectroscopy at 2.8 µm.
abstract: We report on the development of a Faraday rotation spectroscopy (FRS) instrument using a DFB diode laser operating at 2.8 µm for the hydroxyl (OH) free radical detection. The highest absorption line intensity and the largest gJ value make the Q (1.5) double lines of the 2Π3/2 state (υ = 1 ← 0) at 2.8 µm clearly the best choice for sensitive detection in the infrared region by FRS. The prototype instrument shows shot-noise dominated performance and, with an active optical pathlength of only 25 cm and a lock-in time constant of 100 ms, achieves a 1σ detection limit of 8.2 × 10(8) OH radicals/cm3.
authors.affiliation: Laboratoire de Physicochimie de l’Atmosphère, Université du Littoral Côte d’Opale, 189A Av Maurice Schumann, 59140 Dunkerque, France.
authors.forename: Weixiong
authors.initials: W
authors.lastname: Zhao
authors.forename: Gerard
authors.initials: G
authors.lastname: Wysocki
authors.forename: Weidong
authors.initials: W
authors.lastname: Chen
authors.forename: Eric
authors.initials: E
authors.lastname: Fertein
authors.forename: David
authors.initials: D
authors.lastname: Le Coq
authors.forename: Denis
authors.initials: D
authors.lastname: Petitprez
authors.forename: Weijun
authors.initials: W
authors.lastname: Zhang
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D017665:Hydroxyl Radical / Q000032:analysis*; D054023:Lasers, Semiconductor; D012399:Rotation; D013057:Spectrum Analysis / Q000295:instrumentation*
chemical_list: D017665:Hydroxyl Radical